The present invention relates generally to shock absorbing suspension devices. More particularly, it relates to shock absorbing devices of the type which are typically mounted to vehicles and which use both an elastomeric shear spring and flow of fluid through a restricted orifice for absorbing shock, structural leveling and energy dissipation. Known shock absorbers of the type described include those disclosed in commonly assigned co-pending U.S. patent application Ser. No. 950,949, filed Oct. 13, 1978 now abandoned, with a continuation application Ser. No. 214,771, filed Dec. 9, 1980, in the name of L. Dale Coad.
In the Coad application an expandible and contractible elastomeric bladder for separating a gas chamber from a fluid chamber in a viscous spring damper was provided for varying the spring rate of the damper, calibrating the damper or leveling a load supported thereby.
Dynamic operating characteristics of such dampers are chiefly limited to spring rate, damping response, cyclical active energy consumption and the dissipation percentage thereof. Prior art devices of the type described have suffered from the problems of variable spring rate with a minimal damping response during compressive motion, and in rebound motion react with irregular types of damping dependent on load and frequency. Prior art devices have also suffered from a rapidly increasing spring rate as deflection of such a device increases, thereby giving a rough ride to a vehicle containing such devices and incurring high deflection shocks.
The present invention contemplates a new and improved viscous spring damper which exhibits a load supporting capacity and improved operating characteristics over prior viscous spring dampers. The device is wholly contained, simple in design, economical to manufacture, readily adaptable to a plurality of energy dissipation uses, and provides improved shock absorption and energy dissipation.